import 'package:flutter/material.dart';

void main() => runApp(ContextRoute());

class ContextRoute extends StatelessWidget  {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
        home: Scaffold(
          appBar: AppBar(
            title: Text("Context测试"),
          ),
          body: Container(
            child: Builder(builder: (context) {
              // 在 widget 树中向上查找最近的父级`Scaffold`  widget
              Scaffold? scaffold = context.findAncestorWidgetOfExactType<Scaffold>();
              // 直接返回 AppBar的title， 此处实际上是Text("Context测试")
              return scaffold?.appBar as AppBar;
            }),
          ),
        )
    );
  }
}